BASE STATION AND RADIO COMMUNICATION SYSTEM
It is to provide a base station and a radio communication system that are capable of obtaining a desired communication quality by suppressing an influence of interference between a cell in an upper-airspace area and a cell in a terrestrial area, in case that a terminal apparatus is used in the upper-airspace area. A base station 20A of a mobile communication is provided with an antenna 26, a radio communication section 23 for forming a lower first cell 100A and a second cell 200A above the first cell, which are capable of using a same frequency band, and performing a radio communication via the antenna to and from a terminal apparatus 30A in the first cell and a terminal apparatus 40A in the second cell, and a resource assignment section for assigning a radio resource of the same frequency band to a communication with the terminal apparatus in any one cell of the first cell and the second cell in a same time period, and not assigning the radio resource of the same frequency band to communication with the terminal apparatus in an other cell. When the radio resource of the same frequency band is assigned to the terminal apparatus in the second cell, a transmission power control for reducing a transmission power is applied to the terminal apparatus to which the radio resource of the same frequency band is assigned.
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The present invention relates to a base station and a radio communication system of a mobile communication.
BACKGROUND ARTIn conventional mobile communications, a fixed base station such as a macro-cell base station and a small-cell base station (see Patent Literatures 1 and 2, for example), which wirelessly communicates with a terminal apparatus that is a mobile station, is disposed on the ground, and the base station performs wireless communications plural terminal apparatuses.
CITATION LIST Patent Literature
-
- Patent Literature 1: Patent Application Publication No. 2006-093778.
- Patent Literature 2: Patent Application Publication No. 2007-259289.
In recent years, in the mobile communications, there has been a demand for a use of terminal apparatus in an upper airspace. For example, as a method of communicating with a drone (unmanned aerial vehicle), a use of mobile communication via a base station disposed on the ground is under consideration. However, the conventional base station disposed on the ground is generally designed on the premise that the terminal apparatus is located in a terrestrial area (which is an area up to a certain height from the ground, for example, a spatial area below an antenna of the base station), and the use of the terminal apparatus in the upper airspace is unexpected. Therefore, an interference occurs between the cell formed in the terrestrial area and the cell formed in the upper-airspace area, and there is a possibility that a desired communication quality cannot be obtained when the terminal apparatus is used in the upper-airspace area.
Solution to ProblemA base station of a mobile communication according to an aspect of the present invention comprises: an antenna; a radio communication section for forming a first cell below the antenna and a second cell above the first cell, which are capable of using a same frequency band, and performing a radio communication via the antenna to and from a terminal apparatus in the first cell and a terminal apparatus in the second cell; and a resource assignment section for assigning a radio resource of the same frequency band to a communication with the terminal apparatus in any one cell of the first cell and the second cell in a same time period, and not assigning the radio resource of the same frequency band to communication with a terminal apparatus in an other cell, wherein the base station applies a transmission power control for reducing transmission power to the terminal apparatus to which the radio resource of the same frequency band is assigned, when assigning the radio resource of the same frequency band to the terminal apparatus in the second cell.
A base station of a mobile communication according to another aspect of the present invention comprises: an antenna; a radio communication section for forming a first cell below the antenna and a second cell above the first cell, which are capable of using a same frequency band, and performing a radio communication via the antenna to and from a terminal apparatus in the first cell and a terminal apparatus in the second cell; and a resource assignment section for assigning a radio resource of the same frequency band to each of a communication with the terminal apparatus in the first cell and a communication with the terminal apparatus in the second cell in a same time period, wherein the base station applies a transmission power control for reducing a transmission power to the terminal apparatus in the second cell to which the radio resource of the same frequency band is assigned.
A base station of a mobile communication according to yet another aspect of the present invention comprises: an antenna; a radio communication section for forming a first cell below the antenna and a second cell above the first cell, which are capable of using a same frequency band, and performing a radio communication via the antenna to and from a terminal apparatus in the first cell and a terminal apparatus in the second cell; an altitude specifying section for specifying an altitude of the terminal apparatus in the second cell; and a resource assignment section for assigning a radio resource of the same frequency band to each of a communication with the terminal apparatus in the first cell and a communication with the terminal apparatus in the second cell, so that the terminal apparatus in the first cell and the terminal apparatus in the second cell time-divisionally use the same frequency band when the altitude of the terminal apparatus in the second cell becomes less than a predetermined altitude, and the terminal apparatus in the first cell and the terminal apparatus in the second cell simultaneously use the same frequency band when the altitude of the terminal apparatus in the second cell becomes equal to or higher than the predetermined altitude.
In the foregoing base station, the antenna may be an antenna capable of forming a beam of the first cell and a beam of the second cell, and the base station may determine that the altitude of the terminal apparatus in the second cell becomes equal to or higher than the predetermined altitude, in case that the terminal apparatus in the second cell selects the beam of the second cell.
In the foregoing base station, the antenna may be an antenna capable of continuously changing a direction of a beam in a virtual vertical plane centered on the antenna, and the base station may determine that the altitude of the terminal apparatus in the second cell is equal to or higher than the predetermined altitude, in case that an upward angle of the direction of the beam in the virtual vertical plane of the antenna with respect to the horizontal plane is equal to or higher than a predetermined angle.
In the foregoing base station, the antenna may be an antenna capable of forming plural beams having directivities in mutually different directions in a virtual vertical plane centered on the antenna, and the base station may comprise a control section for performing a beamforming control of the antenna so as to form one or more beams forming the first cell and one or more beams forming the second cell.
In the foregoing base station, the antenna may be a Missive antenna in which plural antenna elements are disposed, and the control section may store amplitude and phase values for each antenna element of the antenna, with respect to plural preset beam candidates in mutually different directions, select one of the plural beam candidates based on beam selection information received from the terminal apparatus, and perform a beamforming control so as to form a beam used for a communication with the terminal apparatus based on the amplitude and phase of each antenna element stored for the selected beam candidate.
In the foregoing base station, the antenna may be a Missive antenna in which plural antenna elements are disposed, and the control section may receive radio waves from the terminal apparatus while changing a pointing direction of the antenna in a virtual vertical plane centered on the antenna, detect a direction in which a reception power of radio waves from the terminal apparatus is maximized, and perform a beamforming control so as to form a beam used for a communication with the terminal apparatus in the detected direction.
In the foregoing base station, the base station may comprise a terminal control section for transmitting control information to the terminal apparatus so that the beam formed by the antenna of the terminal apparatus in the second cell is directed toward the base station.
A radio communication system according to yet another aspect of the present invention includes the base station described above, and a terminal apparatus for performing a radio communication with the base station.
In a radio communication system according to yet another aspect of the present invention, plural base stations described above are disposed in a same area.
Advantageous Effects of InventionAccording to the present invention, when a terminal apparatus is used in an upper airspace, a desired communication quality can be obtained by suppressing an influence of an interference between a cell in the upper-airspace area and a cell in the terrestrial area, in case that a terminal apparatus is used in the upper-airspace area.
Hereinafter, embodiments of the present invention are described with reference to the drawings.
A system according to embodiments described herein is a radio communication system for realizing a same-frequency sharing between a terrestrial cell and an upper-airspace cell, in constructing an “upper-airspace service area” for mobile communication that is expected by realizing a drone, a flying car (taxi) and the like, together with a terrestrial service area for mobile communication.
A radio communication system 10 according to the present embodiment includes plural base stations 20A to 20C. The radio communication system 10 may include plural base stations 20A to 20C, and plural terminal apparatuses 30A to 30C and 40A to 40C that respectively perform a radio communication with these base stations. Although three base stations 20A to 20C and six terminal apparatuses 30A to 30C and 40A to 40C are shown in
A radio technology in the radio communication system 10 of the present embodiment is, for example, a radio technology conforming to the LTE (Long Term Evolution)/LTE-Advanced standard. The radio technology in the radio communication system 10 may be another radio technology, such as a radio technology in the next generation standard such as the fifth generation (5G), etc.
The base stations 20A to 20C are respectively called, for example, an eNodeB, gNodeB, etc., and respectively relay a communication between the terminal apparatuses 30A to 30C, 40A to 40C and the mobile communication network.
The terminal apparatuses 30A to 30C and 40A to 40C can connect to the mobile communication network via the base stations 20A to 20C and perform various kinds of communications. The terminal apparatus is called, for example, a user equipment (UE) because it is used by a user of a communication service. Further, the terminal apparatus is sometimes called a mobile station or a mobile equipment because it is movable, and sometimes called a radio equipment.
Cells as radio communication areas formed by the respective base stations 20A to 20C of the present embodiment include terrestrial cells 100A to 100C as first cells formed in a terrestrial service area (hereinafter referred to as “terrestrial area”) A1, and upper-airspace cells 200A to 200C as second cells formed in an upper-airspace service area (hereinafter referred to as an “upper-airspace area”) A2.
Similar to the existing general base stations, the terrestrial cells 100A to 100C are two-dimensional or three-dimensional radio communication areas for respectively performing a radio communication with the terminal apparatuses (hereinafter also referred to as “terrestrial terminals”) 30A, 30B, and 30C located in the terrestrial area A1 which is an area up to a certain height from the ground, for example, an area more downward than the antenna of the base station). On the other hand, the upper-airspace cells 200A to 200C are two-dimensional or three-dimensional radio communication areas for respectively performing a radio communication with the terminal apparatuses (hereinafter also referred to as “upper-airspace terminals”) 40A, 40B, and 40C located in the upper-airspace area A2 more upward than the terrestrial area A1.
The terrestrial terminals 30A, 30B and 30C located in the terrestrial area A1 are, for example, mobile communication terminals such as smart phones and tablet terminals carried by pedestrians, communication terminals mounted on IoT devices (sensors, cameras, etc.) installed in buildings on the ground, communication terminals mounted on terrestrial vehicles such as automobiles and trains, or the like.
The upper-airspace terminals 40A, 40B, and 40C located in the upper-airspace area A2 are, for example, communication terminals respectively mounted on flying objects such as unmanned drones (UAV: Unmanned Aerial Vehicle), manned drones, flying automobiles (taxi), and helicopters, etc. The upper-airspace terminal 40B may be a portable communication terminal such as a smartphone or a tablet terminal possessed by a passenger boarding a flying object such as an aircraft or a helicopter. In the present embodiment, as shown in
In the present embodiment, each of the base stations 20A to 20C, the terrestrial terminals 30A, 30B, 30C, and the upper-airspace terminals 40A, 40B, 40C performs a radio communication using radio resources (frequency resources, time resources) assigned in each cell in a predetermined frequency band. The assignment of radio resources is managed by, for example, the base stations 20A to 20C.
Duplex methods of uplink and downlink for radio communications between the base stations 20A to 20C and the terrestrial terminals 30A, 30B, 30C and between the base stations 20A to 20C and the upper-airspace terminals 40A, 40B, 40C are not limited to specific methods, and may be, for example, a time division duplex method (Time Division Duplex: TDD) or a frequency division duplex method (Frequency Division Duplex: FDD). An access method for the radio communication is not limited to the specific method, but may be, for example, an FDMA (Frequency Division Multiple Access) method, a TDMA (Time Division Multiple Access) method, a CDMA (Code Division Multiple Access) method, or an OFDMA (Orthogonal Frequency Division Multiple Access).
Each of
For example, in the uplink communication from the upper-airspace terminal 40X mounted on the drone 50X to the base station 80B on the ground shown in
In the downlink communication from the base station 80B on the ground to the upper-airspace terminal 40X shown in
In order to avoid the interference, as shown in
Therefore, in the present embodiment, as shown in
Particularly, in the radio communication system of
Moreover, in the example of the radio communication system of
In the present embodiment, an antenna (hereinafter also referred to as “Massive antenna”) is used as the antenna 26, that is composed of an array antenna in which plural antenna elements 26a are two-dimensionally or three-dimensionally disposed as shown in
The shape of the Massive antenna 26 is not limited to a specific shape. For example, the Massive antenna 26 is a planar Massive antenna 26 in which plural antenna elements 26a are disposed in a plane as exemplified in
The beam width and beam direction of the beam 26b formed by the Massive antenna 26 can be controlled in the horizontal and vertical directions. Since the Massive antenna 26 has a large number of antenna elements, for example, 128 at the maximum, it is also possible to assign dedicated radio waves to each user by using a technique such as a beamforming and a spatial multiplexing.
In
The scheduler 22 has a function as a resource assignment section that assigns time resources and predetermined frequency resources (for example, F1, F2, F3, . . . ) in the same frequency band as radio resources to the terminal apparatuses 30A and 40A in the upper-airspace cell 200A and the terrestrial cell 100A. Accordingly, the radio resources are unitarily managed for the upper-airspace cell 200A and the terrestrial cell 100A that are vertically adjacent to each other.
The radio communication section 23 of the base station 20A is configured with a radio communication section 23-1 for upper-airspace cell, which forms the upper-airspace cell 200A, and a radio communication section 23-2 for terrestrial cell 23-2, which forms the terrestrial cell 100A. The radio communication section 23-1 for upper-airspace cell and the radio communication section 23-2 for terrestrial cell are respectively configured with transmission/reception (TX/RX) sections 23a-1 and 23a-2, precoding control sections 23b-1 and 23b-2, and beam control sections 23c-1 and 23c-2, and the configuration of each of the radio communication sections 23-1 and 23-2 is almost the same as each other.
Each of the transmission/reception section 23a-1 and 23a-2 of radio communication sections 23-1 and 23-2 is provided with, for example, a signal amplifying section for amplifying transmission signals and reception signals, a frequency conversion section for converting frequencies of transmission signals and reception signals to frequencies according to the scheduler 22, a radio-signal path switching section, a transmission/reception shared section (DUP: Duplexer), and the like.
The base stations 20A to 20C of the present embodiment respectively forms both cells of the terrestrial cells 100A to 100C and the upper-airspace cells 200A to 200C as shown in
In the case of transmitting data to the terminal apparatuses 30A and 40A of the terrestrial cell 100A and the upper-airspace cell 200A, each of the radio communication sections 23-1 and 23-2 in the base station 20A performs a precoding control on the transmission baseband signal transmitted from the transmission/reception sections 23a-1 and 23a-2 by the precoding control sections 23b-1 and 23b-2 respectively controlled by the beam control sections 23c-1 and 23c-2, and sends transmission signals to the antenna 26 configured with the array antenna. In the case of receiving data from the terminal apparatuses 30A and 40A, the reception data is obtained by the transmission/reception sections 23a-1 and 23a-2 via the precoding control sections 23b-1 and 23b-2, from the reception signal received by the antenna 26.
The radio communication sections 23-1 and 23-2 are respectively is provided with a beamforming function for performing the transmission and reception with a predetermined number of beams, beam width and beam direction using the antenna 26, by the precoding control sections 23b-1 and 23b-2 operating under the control of the beam control sections 23c-1 and 23c-2. Candidate data for plural types of precoding weights (beam patterns), which can be used in the beamforming function, are stored in the storage section of the base station apparatus 21.
Herein, the beamforming function by precoding is a function of preparing plural types (N) of pairs of signal phases (precoding weight matrices) for each antenna element 26a of the antenna 26 (array antenna) so as to receive a beam transmitted in a specific direction or a beam from a specific direction, selecting one precoding weight matrix from among them, performing the precoding control, and controlling the beam. The precoding weight matrix is a matrix that indicates control amount of phase and amplitude to be set for a multi-element antenna 201 when transmitting or receiving radio signals.
In the present embodiment, the terminal apparatuses 30A and 40A, which are located in the terrestrial cell 100A and the upper airspace cell 200A (beam forming area of the antenna 26) of the base station 20A, measure the reception power of the beams, and select the beam with the maximum reception power. This selection result information is sent from the terminal apparatuses 30A and 40A to the base station 20A, and the beam control sections 23c-1 and 23c-2 of the base station 20A select a beam pattern (precoding weight matrix) based on the selection result information, and control the precoding control sections 23b-1 and 23b-2. Thereby, the beam of the antenna 26 is controlled according to the selected precoding weight matrix, and a beam with high directivity toward the terminal apparatuses 30A and 40A is formed.
In this way, the base station 20A in the present embodiment performs a radio communication with the terminal apparatuses 30A and 40A, which are respectively located in the vertically adjacent terrestrial cell 100A and upper-airspace cell 200A, by using highly directional beams formed with the beam forming function. Therefore, between the beams for the terminal apparatuses 30A and 40A respectively located in the vertically adjacent terrestrial cell 100A and upper-airspace cell 200A, the beams can be spatially separated enough.
By concentrating the transmission/reception power in the direction of the terminal apparatus using such beamforming function, an antenna gain is improved, and it is possible to improve the communication quality and the like. Furthermore, as a result of improving the reception power at the base station 20A by improving the antenna gain, by performing the transmission power control on the side of the terminal apparatuses 30A and 40A, it is possible to reduce the transmission power on the side of the terminal apparatuses 30A and 40A. By reducing the transmission power on the side of the terminal apparatuses 30A and 40A, the interference between the vertically adjacent terrestrial cell 100A and upper-airspace cell 200A can be further suppressed. Further, by keeping the transmission power of the terminal apparatuses 30A and 40A low, it is possible to narrow the range where the radio waves reach. Therefore, for example, uplink radio waves from the upper-airspace terminal 40A in the upper-airspace cell 200A are less likely to reach the base stations of other neighboring cells, and a radio-wave interference can be suppressed.
It is noted that, although the base station 20A of the present embodiment adopts the beamforming function with the precoding control, it may adopt a beamforming function with a continuous tracking control that continuously tracks the beam in the direction of the terminal apparatus, for example. The continuous tracking control is realized by, for example, measuring the reception power when radio waves from the terminal apparatuses 30A and 40A located in the terrestrial cell 100A and the upper-airspace cell 200A are received by the base station 20A, detecting the direction in which the reception power is maximized by sweeping the pointing direction of the antenna 26, and setting the beam direction to the detected direction.
Next, a three-dimensional spatial cell configuration by a radio-resource assignment process in the same frequency band in the present embodiment is described.
Configuration Example 1The radio-resource assignment process in the three-dimensional spatial cell configuration of the present configuration example 1 is a non-overlapping assignment process, in which a radio resource of the same frequency band is assigned to the communication with the terminal apparatus in any one cell of the terrestrial cell 100A and the upper-airspace cell 200A in the same time period, and a radio resource of the same frequency band is not assigned to the communication with the terminal apparatus in the other cell.
In the example of
Specifically, for example, in the case of assigning radio resources of the same frequency band to the upper-airspace terminal 40B in the upper-airspace cell 200B, the scheduler 22 in the base station apparatus 21 of the present configuration example 1 confirms that radio resources of the same frequency band are not assigned to the terrestrial terminals in the terrestrial cell 100B, also confirms radio resources of the same frequency band that have already been assigned to other upper-airspace terminals in the upper-airspace cell 200B, and assigns the foregoing radio resources of the same frequency band, which have not yet been assigned to the other upper-airspace terminals, to the upper-airspace terminal 40B in the upper-airspace cell 200B.
Similarly, for example, in the case of assigning radio resources to the terrestrial terminal 30A in the terrestrial cell 100A, the scheduler 22 confirms that radio resources of the same frequency band are not assigned to the terminal apparatuses in the upper-airspace cell 200A, also confirms radio resources of the same frequency band that have already been assigned to the other terrestrial terminals in the terrestrial cell 100A, and assigns the foregoing radio resources of the frequency band, which have not yet been assigned to the other terrestrial terminals, to the terrestrial terminal 30A in the terrestrial cell 100A.
Furthermore, in the present configuration example 1, a transmission power control for reducing a transmission power is applied to the upper-airspace terminal 40B in the upper-airspace cell 200B, in which the radio resource of the same frequency band is assigned to the communication with the base station 20B.
According to the present configuration example 1, in each of the base stations 20A, 20B, and 20C as shown in
Moreover, according to the present configuration example 1, since the antenna gain is improved at each base station and the reception power at each base station can be improved, the transmission power can be greatly reduced by the transmission power control of the upper-airspace terminal 40B in the upper-airspace cell 200B, thereby the interference with the other terrestrial cells 100A and 100C can be greatly reduced.
Configuration Example 2Next, another example of the three-dimensional spatial cell configuration formed by the radio-resource assignment process in the present embodiment (hereinafter, the present example is referred to as “configuration example 2”) is described. In the description of the present configuration example 2, although the base station 20A is described as an example, the same description can be applied to the other base stations 20B and 20C.
Specifically, for example, in the case of assigning radio resources to the upper-airspace terminal 40A in the upper-airspace cell 200A, the scheduler 22 in the base station apparatus 21 of the present configuration example 1 conforms radio resources of the same frequency band that have already been assigned to other upper-airspace terminals in the upper-airspace cell 200A, and assigns radio resources of the same frequency band, which have not yet been assigned to the other upper-airspace terminals, to the terminal apparatus 40A in the upper-airspace cell 200A.
The similar assignment is applied in the case of assigning radio resources to the terrestrial terminal 30A in the terrestrial cell 100A.
Also in the present configuration example 2, a transmission power control for reducing transmission power is applied to the upper-airspace terminal 40A in the upper-airspace cell 200A.
According to the present configuration example 2, in the base station 20A as shown in
On the other hand, according to the present configuration example 2, there will be a case in which communication is performed in the same time period using radio resources in the same frequency band as each other between the terrestrial cell 100A and the upper-airspace cell 200A which are vertically adjacent to each other. Even in this case, since the beams between each of the terminal apparatuses 30A and 40A in the vertically adjacent terrestrial cell 100A and the upper-airspace cell 200A are spatially separated enough, even if radio resources of the same frequency band are assigned to the communications with these terminal apparatuses 30A and 40A at the same time, the interference can be suppressed.
Moreover, according to the present configuration example 2, the transmission power can be reduced by the transmission power control of the upper-airspace terminal 40A in the upper-airspace cell 200A, so that the interference to the terrestrial cells of the other base stations in the vicinity can be reduced.
Herein, in case that the beams between the terminal apparatuses 30A and 40A respectively located in the terrestrial cell 100A and the upper-airspace cell 200A, which are vertically adjacent to each other, are not spatially separated enough, if radio resources of the same frequency band are assigned between the terminal apparatuses 30A and 40A at the same time, the interference may not be sufficiently suppressed. For example, in case that the altitude of the terminal apparatus 40A in the upper-airspace cell 200A is less than the predetermined altitude hth as shown in
Therefore, for the terminal apparatus 40A that is below the predetermined altitude hth among the upper-airspace terminals 40A in the upper-airspace cell 200A, for example, the non-overlapping assignment process of the same frequency resource F1 in the same frequency band as in the above-described configuration example 1 may be adopted, and for the terminal apparatus 40A that is equal to or higher than the predetermined altitude hth, the overlapping assignment process of the same frequency resource F1 in the same frequency band as in the configuration example 2 may be adopted. In this case, the interference can be suppressed more stably.
For the terminal apparatus 40A that is below the predetermined altitude hth, for example, as shown in
On the other hand, in case that the beams between the terminal apparatuses 30A and 40A respectively located in the terrestrial cell 100A and the upper-airspace cell 200A, which are vertically adjacent to each other, are spatially separated enough, the interference is suppressed even if communications of the same frequency resource in the same frequency band are performed simultaneously in these terminal apparatuses 30A and 40A.
In case that the altitude of the upper-airspace terminal 40A is equal to or higher than the predetermined altitude hth in this way, for example, as shown in
Next, yet another example of the three-dimensional spatial cell configuration formed by the radio-resource assignment process in the present embodiment (hereinafter, the present example is referred to as “configuration example 3”) is described. In the description of the present configuration example 3, although the base station 20A is described as an example, the same description can be applied to the other base stations 20B and 20C.
The base station apparatus 21 according to the present configuration example 3 can perform a combination of the time-division duplex process shown in
Specifically, as shown in
In the present configuration example 3, a switching between the simultaneous communication process and the time-division duplex process is performed by a switching control section 23e and a changeover switch 23f. Specifically, the altitude specifying section 23d performs a process of specifying (estimating) the altitude of the upper-airspace terminal 40A in the upper-airspace cell 200A, and sends the processing result (specified altitude) to the switching control section 23e.
The switching control section 23e determines whether or not the altitude related to the received processing result is equal to or higher than the predetermined altitude hth, and switches the processing mode of the changeover switch 23f to the simultaneous communication process when determining that the altitude is equal to or higher than the predetermined altitude hth. As a result, the simultaneous communication process is respectively performed for the upper-airspace terminal 40A in the upper-airspace cell 200A and the terrestrial terminal 30A to which the same frequency resource as the upper-airspace terminal 40A is assigned in the terrestrial cell 100A.
On the other hand, the switching control section 23e switches the processing mode of the changeover switch 23f to the time-division duplex process when determining that the altitude related to the received processing result is less than the predetermined altitude hth. As a result, the time-division duplex process is respectively performed for the upper-airspace terminal 40A in the upper-airspace cell 200A and the terrestrial terminal 30A to which the same frequency resource as the upper-airspace terminal 40A is assigned in the terrestrial cell 100A.
According to the present configuration example 3, it is possible to achieve both of the stable suppression of interference between the terminal apparatuses 30A and 40A, which are respectively located in the vertically adjacent terrestrial cell 100A and the upper-airspace cell 200A and the improvement in frequency utilization efficiency at a high level.
According to the present configuration example 3, for example, it is possible to appropriately cope with movements of the drone 50A as shown in
The altitude estimation process performed by the altitude specifying section 23d is not particularly limited as long as it can specify (estimate) the altitude of the terminal apparatus 40A in the upper-airspace cell 200A. For example, the base station apparatus 21 of the base station 20A may receive the measurement result of the altimeter mounted on the drone 5 from the terminal apparatus 40A, and the altitude specifying section 23d may specify the altitude of the terminal apparatus 40A based on the received measurement result.
Further, for example, the altitude specifying section 23d may specify the altitude of the upper-airspace terminal 40A based on control information when the beam control section 23c-1 performs a beam control.
For example, as shown in
For example, in the case of adopting a beam forming function by a continuous tracking control that continuously tracks the beam in the direction of the terminal apparatus, the altitude of the upper-airspace terminal 40A may be specified using information on the beam angle 9 (angle of the beam direction in the virtual vertical plane of the antenna 26 with respect to the horizontal plane), which is control information for the continuous tracking control, as shown in
In the above-described embodiment (including each configuration example), the upper-airspace terminal 40A may be provided with the beam forming function, and the beam formed by the antenna of the upper-airspace terminal 40A may be controlled to be directed toward the base station 20A as shown in
By such beamforming function in the upper-airspace terminal 40A, the transmission/reception power of the terminal apparatus 40A in the upper-airspace cell 200A is concentrated in the direction of the base station 20A, thereby the antenna gain is improved, accordingly the communication quality, etc. can be improved.
Further, as shown in
In addition, since the antenna gain is improved as described above, the transmission power of the upper-airspace terminal 40A in directions other than the direction of the base station 20A is reduced. As a result, the uplink radio waves from the upper-airspace terminal 40A are less likely to affect the other base stations 20B and 20C in the vicinity, and a giving interference from the upper-airspace terminal 40A can be suppressed.
It is noted that, the process steps and configuration elements of the radio communication system and the terminal apparatus (UE, user apparatus, mobile station) described in the present description can be implemented with various means. For example, these process steps and configuration elements may be implemented with hardware, firmware, software, or a combination thereof.
With respect to hardware implementation, means such as processing units or the like used for establishing the foregoing steps and configuration elements in entities (for example, various kinds of radio communication apparatuses, Node B, terminal apparatus, hard disk drive apparatus, or optical disk drive apparatus) may be implemented in one or more of an application-specific IC (ASIC), a digital signal processor (DSP), a digital signal processing apparatus (DSPD), a programmable logic device (PLD), a field programmable gate array (FPGA), a processor, a controller, a microcontroller, a microprocessor, an electronic device, other electronic unit, computer, or a combination thereof, which are designed so as to perform a function described in the present specification.
With respect to the firmware and/or software implementation, each section used for establishing the foregoing configuration elements may be implemented with a program (for example, code such as procedure, function, module, instruction, etc.) for performing a function described in the present specification. In general, any computer/processor readable medium of materializing the code of firmware and/or software may be used for implementation of means such as processing units and so on for establishing the foregoing steps and configuration elements described in the present specification. For example, in a control apparatus and storage apparatus, the firmware and/or software code may be stored in a memory and executed by a computer or processor. The memory may be implemented within the computer or processor, or outside the processor. Further, the firmware and/or software code may be stored in, for example, a medium capable being read by a computer or processor, such as a random-access memory (RAM), a read-only memory (ROM), a non-volatility random-access memory (NVRAM), a programmable read-only memory (PROM), an electrically erasable PROM (EEPROM), a FLASH memory, a floppy (registered trademark) disk, a compact disk (CD), a digital versatile disk (DVD), a magnetic or optical data storage unit, or the like. The code may be executed by one or more of computers and processors, and a certain aspect of functionalities described in the present specification may by executed by a computer or processor.
The medium may be a non-transitory recording medium. Further, the code of the program may be executable by being read by a computer, a processor, or another device or an apparatus machine, and the format is not limited to a specific format. For example, the code of the program may be any of a source code, an object code, and a binary code, and may be a mixture of two or more of those codes.
The description of embodiments disclosed in the present specification is provided so that the present disclosures can be produced or used by those skilled in the art. Various modifications of the present disclosures are readily apparent to those skilled in the art and general principles defined in the present specification can be applied to other variations without departing from the spirit and scope of the present disclosures. Therefore, the present disclosures should not be limited to examples and designs described in the present specification and should be recognized to be in the broadest scope corresponding to principles and novel features disclosed in the present specification.
REFERENCE SIGNS LIST
-
- 10: radio communication system
- 20A to 20C: base station
- 21: base station apparatus
- 22: scheduler
- 23: radio communication section
- 23-1: radio communication section for upper-airspace cell
- 23-2: radio communication section for terrestrial cell
- 23a-1, 23a-2: transmission/reception section
- 23b-1, 23b-2: precoding control section
- 23c-1, 23c-2: beam control section
- 23d: altitude specifying section
- 23e: switching control section
- 23f: changeover switch
- 26: antenna
- 26a: antenna element
- 30A to 30C: terminal apparatus (terrestrial terminal)
- 40A to 40C: terminal apparatus (upper-airspace terminal)
- 50A to 50C: drone
- 100A to 100C: terrestrial cell
- 105: beam for ground
- 200A to 200C: upper-airspace cell
- 205: beam for upper airspace
- A1: terrestrial area
- A2: upper-airspace area
Claims
1. A base station of a mobile communication, comprising:
- an antenna;
- a radio communication section for forming a first cell below the antenna and a second cell above the first cell, and performing a radio communication via the antenna to and from a terminal apparatus in the first cell and a terminal apparatus in the second cell, the first cell and the second cell being capable of using a same frequency band; and
- a resource assignment section for assigning a radio resource of the same frequency band to a communication with the terminal apparatus in any one cell of the first cell and the second cell in a same time period, and not assigning the radio resource of the same frequency band to a communication with a terminal apparatus in an other cell, and
- wherein the base station applies a transmission power control for reducing a transmission power to the terminal apparatus to which the radio resource of the same frequency band is assigned, when assigning the radio resource of the same frequency band to the terminal apparatus in the second cell.
2. A base station of a mobile communication, comprising:
- an antenna;
- a radio communication section for forming a first cell below the antenna and a second cell above the first cell, and performing a radio communication via the antenna to and from a terminal apparatus in the first cell and a terminal apparatus in the second cell, the first cell and the second cell being capable of using a same frequency band; and
- a resource assignment section for assigning a radio resource of the same frequency band to each of a communication with the terminal apparatus in the first cell and a communication with the terminal apparatus in the second cell in a same time period, and
- wherein the base station applies a transmission power control for reducing a transmission power to the terminal apparatus in the second cell to which the radio resource of the same frequency band is assigned.
3. A base station of a mobile communication, comprising:
- an antenna;
- a radio communication section for forming a first cell below the antenna and a second cell above the first cell, and performing a radio communication via the antenna to and from a terminal apparatus in the first cell and a terminal apparatus in the second cell, the first cell and the second cell being capable of using a same frequency band;
- an altitude specifying section for specifying an altitude of the terminal apparatus in the second cell; and
- a resource assignment section for assigning a radio resource of the same frequency band to each of a communication with the terminal apparatus in the first cell and a communication with the terminal apparatus in the second cell, so that the terminal apparatus in the first cell and the terminal apparatus in the second cell time-divisionally use the same frequency band when the altitude of the terminal apparatus in the second cell becomes less than a predetermined altitude, and the terminal apparatus in the first cell and the terminal apparatus in the second cell simultaneously use the same frequency band when the altitude of the terminal apparatus in the second cell becomes equal to or higher than the predetermined altitude.
4. The base station according to claim 3,
- wherein the antenna is an antenna capable of forming a beam of the first cell and a beam of the second cell, and
- wherein the base station determines that the altitude of the terminal apparatus in the second cell becomes equal to or higher than the predetermined altitude, in case that the terminal apparatus in the second cell selects the beam of the second cell.
5. The base station according to claim 3,
- wherein the antenna is an antenna capable of continuously changing a direction of a beam in a virtual vertical plane centered on the antenna, and
- wherein the base station determines that the altitude of the terminal apparatus in the second cell is equal to or higher than the predetermined altitude, in case that an upward angle of the direction of the beam in the virtual vertical plane of the antenna with respect to the horizontal plane is equal to or higher than a predetermined angle.
6. The base station according to claim 1,
- wherein the antenna is an antenna capable of forming plural beams having directivities in mutually different directions in a virtual vertical plane centered on the antenna, and
- wherein the base station comprises a control section for performing a beamforming control of the antenna so as to form one or more beams forming the first cell and one or more beams forming the second cell.
7. The base station according to claim 6,
- wherein the antenna is a Massive antenna in which plural antenna elements are disposed, and
- wherein the control section: stores amplitude and phase values for each antenna element of the antenna, with respect to plural preset beam candidates in mutually different directions; selects one of the plural beam candidates based on beam selection information received from the terminal apparatus; and performs a beamforming control so as to form a beam used for a communication with the terminal apparatus based on the amplitude and phase of each antenna element stored for the selected beam candidate.
8. The base station according to claim 6,
- wherein the antenna is a Massive antenna in which plural antenna elements are disposed, and
- wherein the control section: receives radio waves from the terminal apparatus while changing a pointing direction of the antenna in a virtual vertical plane centered on the antenna; detects a direction in which a reception power of radio waves from the terminal apparatus is maximized; and performs a beamforming control so as to form a beam used for a communication with the terminal apparatus in the detected direction.
9. The base station according to claim 1:
- a terminal control section for transmitting control information to the terminal apparatus so that the beam formed by the antenna of the terminal apparatus in the second cell is directed toward the base station.
10. A radio communication system, comprising:
- the base station according to claim 1; and
- a terminal apparatus for performing a radio communication with the base station.
11. A radio communication system in which plural base stations according to claim 1 are disposed in a same area.
12. The base station according to claim 2,
- wherein the antenna is an antenna capable of forming plural beams having directivities in mutually different directions in a virtual vertical plane centered on the antenna, and
- wherein the base station comprises a control section for performing a beamforming control of the antenna so as to form one or more beams forming the first cell and one or more beams forming the second cell.
13. The base station according to claim 3,
- wherein the antenna is an antenna capable of forming plural beams having directivities in mutually different directions in a virtual vertical plane centered on the antenna, and
- wherein the base station comprises a control section for performing a beamforming control of the antenna so as to form one or more beams forming the first cell and one or more beams forming the second cell.
14. The base station according to claim 12,
- wherein the antenna is a Massive antenna in which plural antenna elements are disposed, and
- wherein the control section: stores amplitude and phase values for each antenna element of the antenna, with respect to plural preset beam candidates in mutually different directions; selects one of the plural beam candidates based on beam selection information received from the terminal apparatus; and performs a beamforming control so as to form a beam used for a communication with the terminal apparatus based on the amplitude and phase of each antenna element stored for the selected beam candidate.
15. The base station according to claim 13,
- wherein the antenna is a Massive antenna in which plural antenna elements are disposed, and
- wherein the control section: stores amplitude and phase values for each antenna element of the antenna, with respect to plural preset beam candidates in mutually different directions; selects one of the plural beam candidates based on beam selection information received from the terminal apparatus; and performs a beamforming control so as to form a beam used for a communication with the terminal apparatus based on the amplitude and phase of each antenna element stored for the selected beam candidate.
16. The base station according to claim 12,
- wherein the antenna is a Massive antenna in which plural antenna elements are disposed, and
- wherein the control section: receives radio waves from the terminal apparatus while changing a pointing direction of the antenna in a virtual vertical plane centered on the antenna; detects a direction in which a reception power of radio waves from the terminal apparatus is maximized; and performs a beamforming control so as to form a beam used for a communication with the terminal apparatus in the detected direction.
17. The base station according to claim 13,
- wherein the antenna is a Massive antenna in which plural antenna elements are disposed, and
- wherein the control section: receives radio waves from the terminal apparatus while changing a pointing direction of the antenna in a virtual vertical plane centered on the antenna; detects a direction in which a reception power of radio waves from the terminal apparatus is maximized; and performs a beamforming control so as to form a beam used for a communication with the terminal apparatus in the detected direction.
18. The base station according to claim 2, comprising:
- a terminal control section for transmitting control information to the terminal apparatus so that the beam formed by the antenna of the terminal apparatus in the second cell is directed toward the base station.
19. The base station according to claim 3, comprising:
- a terminal control section for transmitting control information to the terminal apparatus so that the beam formed by the antenna of the terminal apparatus in the second cell is directed toward the base station.
Type: Application
Filed: Feb 8, 2022
Publication Date: May 23, 2024
Applicant: SoftBank Corp. (Tokyo)
Inventor: Teruya Fujii (Tokyo)
Application Number: 18/279,248